Treatment of HIV-1 infection with highly active antiretroviral therapy has led to sustained viral suppression in the plasma in a large number of children. However, studies have suggested that the integrated provirus in resting CD4+ T lymphocytes could be a source of reactivatable virus and maintain drug-resistant virus. We evaluated the resistance-related mutations in children receiving antiretroviral therapy with prolonged viral suppression. Thirty-two peripheral blood mononuclear cell samples from 16 children with viral loads that had been below detection limits for at least 12 months were obtained at two different time points and the DNAs sequenced. The median CD4 cell count was 1,016 cells/mm³ (347-2,588) and 938 cells/mm³ (440-3,038) at the first and second time points, respectively. The median follow-up time was 15 months (9-27). Six (37.5%) and seven (43.75%) of the 16 patients showed at least one NRTI-associated mutation in the first and second samples, respectively. Two out of 16 (12.5%) had an NNRTI-associated mutation at the first time point and three out of 16 (18.75%) at the second. In addition, 14 out of 16 (87.5%) had at least one PI-associated mutation at both time points. Despite plasma HIV-1 RNA suppression for at least 12 months, resistance-related mutations from previous antiretroviral failures could still be detected in archival virus. Furthermore, viral evolution occurred at the reverse transcriptase region in spite of viral suppression to levels below 400 copies/mL. Persistence of archival resistant virus may be relevant when considering future treatment options.

The CCR5 molecule, a chemokine receptor, is the most important co-receptor for macrophage-tropic HIV-1. A 32-bp deletion in the gene encoding CCR5 (CCR5-del32) confers nearly complete resistance to HIV-1 infection in homozygotes, and slows the rate of progression to AIDS in heterozygous adults. The aim of this study was to describe the CCR5 genotypes and the characteristics of HIV disease progression in perinatally infected children. From a total of 51 children analyzed for the CCR5-del32 mutation, 18 (35%) were considered to be rapid progressors, 28 (55%) were moderate progressors and 5 (10%) were slow progressors. A portion of the CCR5 gene was amplified by PCR from genomic DNA followed by agarose gel electrophoresis. Forty-nine children (96%) carried the homozygous wild type genotype for CCR5 while 2 (4%) carried the heterozygous wt/del32 genotype. In the population studied, the CCR5 genotype was unable to account for the differences in pattern of the disease progression among the three groups (rapid, moderate and slow progressors), and the allele frequency of CCR5-del32 was too low to allow statistical comparisons with adequate resolving power. Studies on larger populations may help to further elucidate the role of this allele and other host factors in the regulation of HIV-1 pathogenesis in children.

This study evaluates clinical, virological and immunological responses to antiretroviral (ARV) therapy based on Lopinavir/ritonovir (LPV/r) in previously protease -inhibitor-experienced children. The study included 29 Brazilian children (median age = 5.91 years) who had failed previous ARV therapy and had begun a regimen based on LPV/r. At 12 months follow-up, a good virological response to LPV/r therapy was defined as achieving an undetectable viral load or as a decrease in plasma HIV RNA levels to > 1 log. A good immunological response was defined as an increase in CD4+ cell count from baseline sufficient to attain a better CDC immune stage classification. The number of infectious episodes 12 months before and 12 months after beginning LPV/r was assessed. Sixteen (55.2%) and 19 (65.5%) of 29 patients exhibited good virological and immunological responses, respectively. Baseline CD4+ values (>500) predicted both virological and immunological responses (p<0.05). Older children were less likely to develop an immunological response (p<0.001) than younger children. Nine children receiving 3 ARV drugs plus LPV/r showed an immunological response (100%) compared to 10/20 (50%) children receiving 2 drugs plus LPV/r (p=0.01). A lower number (n<5) of infectious episodes was noted after 12 months follow-up in children using the LPV/r regimen (p=0.006). There was a positive correlation between children whose baseline CD4+ values were greater than 500 cells/mm³ and virological responses. Although virological responses to therapy were seen in about half the children (55.2%), the use of HAART containing LPV/r provided clinical and immmunological benefits.